Performance Evaluation of Carrier Interferometry Implementations of MC-CDMA Over a Wideband Channel Suffering Phase Noise

Abstract

In this paper the performance of carrier interferometry (CI) and pseudo-orthogonal carrier interferometry (PO-CI) [B. Natarajan et al., November 2001] implementations of multi-carrier code division multiple access (MC-CDMA) are investigated. Comparisons are made with the performance of traditional MC-CDMA (incorporating Hadamard-Walsh spreading codes) [S. Hara and R. Prasad, December 1997], [N. Yee and J.P Linnartz, 1993] and coded orthogonal frequency division multiplexing (COFDM) [R. Van Nee and R. Prasad, 2000]. These systems are simulated over a 20 MHz bandwidth, wideband, wide-sense stationary, statistically uncorrelated Rayleigh fading channel suffering additive white Gaussian noise (AWGN) and phase noise. The two channel models employed are consistent with the model B 'indoor and office' and model B 'outdoor to indoor and pedestrian' test environment specifications proposed by ETSI for UMTS terrestrial radio access (UTRA). The BPSK CI system was found to outperform both of the equivalent COFDM and MC-CDMA systems, providing 1 dB and 1.5 dB performance gains respectively at a bit error rate (BER) of 10/sup -3/. The BPSK PO-CI system, shown to offer twice the capacity of the equivalent MC-CDMA, COFDM and CI systems, was found to offer the same performance as MC-CDMA, For higher order modulation schemes, the CI system's performance was found to equal that of the equivalent MC-CDMA system, whilst the performance of PO-CI was found to be very poor. In the presence of phase noise, the CI system was found to outperform the MC-CDMA and COFDM systems, suffering a far lower performance loss for a given level of phase noise and providing a softer fail as this level was increased. This soft fail characteristic was also observed in the PO-CI system.